When Domon briefly glimpsed Rain embedded in a wall. However, she was quickly enveloped by the wall as it manifested a smaller combat form to protect its core unit. This "Core Devil Gundam" was said to be a manifestation of Rain's desire to keep Domon away due to her feelings of grief, as she felt the crimes of her father's were hers as well. It overwhelmed its foe with its vastly superior power and regenerative abilities; to make matters worse, any damage Domon inflicted to the unit caused Rain to suffer equal amounts of pain due to her link with the Devil Gundam.

In his moment of weakness, Domon finally admitted his love for Rain. After she heard his cries, Rain broke from the Devil Gundam. Despite losing its core life unit, the Devil Gundam remained functional - although it appeared to enter a feral state - and attempted to attack Domon and Rain. In response, the duo combined their power and love into a new attack, the "Sekiha Love Love Tenkyoken", which pierced through the core Devil Gundam before it obliterated it completely. With its core unit completely destroyed, the Colony Devil Gundam lost all power, imploded, and ended the conflict once and for all.